Instruction manual

85
Relay Input Assignment
Click on the arrow of the pull down menu and select the input that will be used to control the
relay. See Section 6.2 for details.
Current Reading
This field is for information only, and will display the calibrated reading from the sensor that is
assigned to control the relay.
Status
This menu is for information only, and displays whether the output is “Off” or “On” and if on, for
how much time, as well as any alarm conditions. Possible status messages are; Off, Off/Manual,
On/Time counting up (if activated based on sensor input), Off/Time counting down or On/Time
counting down/Hand (for manual relay activation). Possible error messages are Timeout and
Interlock. See section 8.1 for a complete description of error messages.
Reset Timeout
There is a button called “Reset Timeout” which is used to reset the output if it has been activated
for longer than the time limit imposed in the “Output Time Limit” menu described below.
Custom Name
This menu allows you to rename the output if desired. Type the new name into the text box.
Set Point
Type in the text box the process value at which you want the relay to activate. The set point value
is limited to the range of the assigned input.
Control Direction
Click on the radio button to select between “Force Lower” or “Force Higher”.
Dead Band
Type in the text box the process value away from the set point at which the relay will deactivate.
For example, if you are forcing the conductivity lower, your set point is 2000 µS/cm, and your
dead band is 100 µS/cm, then the relay will activate at 2001 µS/cm and deactivate at 1900 µS/cm.
The purpose of the dead band is to prevent rapid cycling of the relay open and closed, which can
shorten its life. The dead band should be set for the lowest value that still prevents the relay from
chattering.
Time Period
To superimpose Percent Time to Set Point (PTSP) on the on/off control algorithm, select a timer
period between 1 and 1440 minutes. To use standard on/off control set the time period to 0. PTSP
uses the time period and the Percent of Time Period to Feed menus to cycle the relay on and off
even though the set point has not yet been reached.
Percent of Time Period to Feed
Select the duty cycle of the relay by entering the percent of the time period for the relay to be
active.